It is estimated that 25 million gallons of condensate and 21,000 gallons of acidic oil are discharged from compressed air systems each day in the United States. With the discharge of oil/water mixtures into sanitary drains no longer being possible in view of environmental considerations and paying hauling companies to remove the bulk effluent being expensive, procedures for handling oil/water mists generated by air compressors and similar equipment have become increasingly important. Commercially available oil/water separators separate the oil as a liquid by trapping the mist and permitting the oil to coalesce, thereby forming a film on the surface of the condensate which can be siphoned off, leaving partially cleaned water. This water is then further purified using activated charcoal and can then be discharged. The process leaves the oil-impregnated charcoal and liquid oil for disposal.
The affinity of polypropylene for oil is well-known. For example, in "Oil Spill Recovery System," U.S. Pat. No. 5,169,519, which issued to Norman E. Elsas on Dec. 8, 1992, the author describes an oil spill recovery system which deposits a polypropylene quilt onto an oil spill on water. After interacting with the oil film, the quilt is retrieved and the oil squeezed therefrom. Similarly, in "Polypropylene Oil Removal Structure," U.S. Pat. No. 4,332,854, which issued to James H. Parker on Jun. 1, 1982, the inventor describes a loose, fluffy polyolefin mass having many interstices formed throughout the mass for use in the removal of spilled oil from the surface of a body of water. U.S. Pat. No. 4,737,394 for "Article For Absorbing Oils," which issued to Dimitri P. Zafiroglu on Apr. 12, 1988, describes a porous outer fabric which consists of a nonwoven fibrous layer of polypropylene or polyethylene that is stitch-bonded with an elastic thread, for enclosing fibrous oil-absorbing particles. The fabric has sufficient porosity to permit oil to pass through rapidly to the absorbent material.
There are many polyolefin-based oil filters. In "Oil-Water Separation Filters," U.S. Pat. No. 4,212,733, which issued to Yuzuru Goto et al. on Jul. 15, 1980, an oil-water separation filter which is constructed from a sintered polyethylene powder bonded to a fibrous layer is described. When passed through such a filter, the water containing the oil becomes clear and has an extremely low oil content. In "Filtration Process Using Polyolefin Fibrids As Filter Aids," U.S. Pat. No. 4,274,971, which issued to Edmund Hartinger et al., on Jun. 23, 1981, the authors discuss the use of crystalline polyolefins which, after being rendered hydrophilic, are added to the suspension to be filtered, as aids in the filtration process. U.S. Pat. No. 4,960,520 for "Method Of Removing Organic Volatile And Semi-Volatile Contaminants From An Aqueous Solution," which issued to Michael J. Semmens on Oct. 2, 1990, describes the use of hollow-fiber membranes of microporous polypropylenes coated with plasma polymerized disiloxane and potted in a module for removing contaminants from aqueous solution. Contaminated water is pumped through the fibers. The contaminants diffuse across the membranes and into an awaiting oil bath for removal thereof. The result is clean water and a smaller volume of more highly contaminated oil.
Air compressors generally have storage tanks called "receivers" which collect and store the high-pressure air. As the air is compressed, moisture in the air condenses and collects in the receivers. Small quantities of oil, used to lubricate the air compressor, are also carried into the receiver, where it condenses and mixes with the water. The water and oil must be periodically drained from the receiver, a process which was in the past simply accomplished by discharging ("blow down") the receiver into a floor drain.
Accordingly, it is an object of the present invention to provide an oil/water separator having low impedance to airflow, while separating oil and water in a mist thereof entrained in the airflow.
Another object of the present invention is to provide an oil/water separator having low impedance to airflow, while removing sufficient oil from water in a mist thereof entrained in the airflow that the water may be safely discharged into sanitary drains.
Yet another object of the present invention is to provide an oil/water separator having low impedance to airflow, while removing sufficient oil from water in a mist thereof entrained in the airflow that the water may be safely discharged into sanitary drains while the oil is sequestered in the separator.
Still another object of the present invention is to provide an oil/water separator for removing oil from water from any source thereof.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.